Metastable β-Ti alloys have attracted significant attention in biomedical applications due to their multiple deformation mechanisms and favorable mechanical properties. However, limited studies have focused on the compression behaviour of solution-treated high-Mo binary Ti–Mo alloys. In this study, Ti-20Mo and Ti-23Mo alloys were designed using electronic parameters, namely, the Bo–Md method and molybdenum equivalence (Moeq), to predict phase stability and underlying deformation mechanisms. Phase evolution and deformation behaviour after compression testing were investigated using X-ray diffraction (XRD) and optical microscopy (OM). Both alloys exhibited β phase, stress-induced α″ martensite, and R phases, with dislocation slip and mechanical twinning identified as dominant deformation mechanisms. The ultimate compressive strength increased from 1308 MPa (Ti-20Mo) to 2226 MPa (Ti-23Mo), while the compressive yield strength increased from 911 MPa to 1748 MPa. Apparent compressive strain also increased from 30% to 37% with increasing Mo content. Conversely, hardness decreased slightly from 386 HV0.5 to 362 HV0.5, attributed to enhanced β-phase stability. These results demonstrate that increasing Mo content enhances β-phase retention, leading to improved compressive strength and ductility while suppressing extensive stress-induced martensitic formation. The mechanical response of these alloys indicates strong potential for load-bearing biomedical applications, particular for vascular stents applications.